Do i need to dispose of this Image instance?

Question

I'm making a simple Image Debugger Visualizer. Code is below. I'm not sure if i need to manually dispose of the Image instance? Because i'm making a windows Form window and the PictureBox inside that contains my dynamic image .. do i need to add some special code when the form is terminating, to dispose of this?

here's the code..

using System.Diagnostics;
using System.Drawing;
using System.Windows.Forms;
using Microsoft.VisualStudio.DebuggerVisualizers;
using DebuggerVisualizers;

[assembly: DebuggerVisualizer(
    typeof (ImageDebuggerVisualizer),
    typeof (VisualizerObjectSource),
    Target = typeof (Image),
    Description = "Image Visualizer")]

namespace DebuggerVisualizers
{
    public class ImageDebuggerVisualizer : DialogDebuggerVisualizer
    {
        protected override void Show(IDialogVisualizerService windowService, IVisualizerObjectProvider objectProvider)
        {
            Image image = (Image) objectProvider.GetObject();
            Form form = new Form
                           {
                               Text = ("Image Visualizer - " + image.HorizontalResolution + " " + image.VerticalResolution),
                               Width = image.Width,
                               Height = image.Height
                           };

            PictureBox pictureBox = new PictureBox {Image = image, SizeMode = PictureBoxSizeMode.AutoSize};
            form.Controls.Add(pictureBox);
            form.ShowDialog();
        }
    }
}

thanks for any help :)

score 2 · Accepted Answer · answered Nov 25 '08 at 15:03

2

Change your Show method to this:

protected override void Show(IDialogVisualizerService windowService,
    IVisualizerObjectProvider objectProvider)        
{            
    Image image = (Image) objectProvider.GetObject();
    using (Form form = new Form())
    {            
        PictureBox pictureBox = new PictureBox();    
        pictureBox.Image = image;        
        form.Controls.Add(pictureBox); 
        form.ShowDialog();
    } 
}

The using(){} block will call Dispose on the form after it closes, which will dispose of everything on the form also.

answered Nov 25 '08 at 15:03

MusiGenesis

74,184
40
190
334

So the form dialog will not terminate when we leave the scope of the SHOW method (or more importantly, leave the scope of the USING block? – Pure.Krome Nov 26 '08 at 01:52
The form will be closed but still around after the ShowDialog() call. The using(){} block will call Dispose on the form, so it will be gone outside the scope of the block (along with anything on it that needs to be disposed). – MusiGenesis Nov 26 '08 at 03:05

score 1 · Answer 2 · answered Nov 25 '08 at 13:55

1

The picture box control does not dispose of the image, so this is up to you, yes.

answered Nov 25 '08 at 13:55

Lasse V. Karlsen

380,855
102
628
825

System.Drawing.Image implements IDisposable so you should call dispose on it. – Matt Lacey Nov 25 '08 at 14:15
Ok .. so what is the override i'll need for when a form is destroyed? – Pure.Krome Nov 25 '08 at 14:20

score 1 · Answer 3 · answered Nov 25 '08 at 14:35

Um, I'm going to go out on a limb here and say you shouldn't dispose of it.

I never created a visualizer, and I don't exactly know Visual Studio does this, but it seems to me that if you dispose of an object in a visualizer, you might break the code you're debugging.

It all comes down to this line:

Image image = (Image) objectProvider.GetObject();

If that object isn't a clone, then you will be disposing the object created by the code that's being debugged. The code won't be expecting that object to be suddenly disposed, and S will hit the fan, causing you at least to have to restart your debugging.

I'd play it safe and NOT dispose of it. Think about it--you're debugging. That's not a long lived process. If you do leak a bitmap handle, its not the end of the world...

I don't think the OQ is suggesting disposing of the image immediately, which would be a big problem. He's talking about whether to explicitly dispose of the created PictureBox when the form closes. — MusiGenesis, Nov 25 '08 at 14:42

score 0 · Answer 4 · answered Nov 25 '08 at 14:45

I think you should dispose it. It should be quite easy, just add a using() at the first line of your method (around the Image image = ... line) and end it after the form.ShowDialog().

I think it is safe to dispose the image, for if you want to change the visualized object you must call one of the TransferData/TranferObject/ReplaceDat/ReplaceObject methods to send it back.

Do i need to dispose of this Image instance?

4 Answers4